<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright 2008 XBRL International. All Rights Reserved. -->
<?xml-stylesheet type="text/xsl" href="../stylesheets/functionDefinition.xsl"?>
<function
  xmlns="http://xbrl.org/2008/function"
  xmlns:reg="http://xbrl.org/2008/registry"
  xmlns:xhtml="http://www.w3.org/1999/xhtml"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:xfi="http://www.xbrl.org/2008/function/instance" 
  xmlns:xfie="http://www.xbrl.org/2008/function/instance/error" 
  xmlns:xbrli="http://www.xbrl.org/2003/instance" 
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xsi:schemaLocation="
  http://xbrl.org/2008/registry ../schemas/registry.xsd
  http://xbrl.org/2008/function ../schemas/function.xsd
  ">

  <lastUpdated moment="2008-01-23T00:00:00" />

  <owners>
    <reg:owner id="geoff">
       <reg:name>Geoff Shuetrim</reg:name>
       <reg:affiliation>Galexy</reg:affiliation>
       <reg:email>geoff@galexy.net</reg:email>
       <reg:assumedOwnership moment="2008-02-14T00:00:00" />
    </reg:owner>
  </owners>

  <summary>
    Return the period start dateTime for finite durations and the instant
    dateTime for instants.
  </summary>

  <documentation>
    <xhtml:p>
    For the dates, XBRL uses a union of date and dateTime. When a date
    is specified, it should be expanded to a dateTime as specified in
    the XBRL specification. Note that this expansion differs for start dates
    and instant dates.  
    </xhtml:p>
  </documentation>
  
  <reference xlink:type="simple" xlink:href="http://www.xbrl.org/Specification/XBRL-RECOMMENDATION-2003-12-31+Corrected-Errata-2006-12-18.htm#_Toc156209161">
    XBRL 2.1 Section 4.7.2
  </reference>

  <signature name="xfi:period-start">
    <input name="period" type="element(xbrli:period)">
      <xhtml:p>
        The period for which to obtain the period start.
      </xhtml:p>
    </input>
    <output type="xs:dateTime">
      <xhtml:p>
        Return the period start dateTime for finite durations and the instant
        dateTime for instants.
        For a start date without time, the dateTime returned is the midnight at the
        start of the date reported, as if the time portion were "T00:00:00".  For
        an instant date without time, the dateTime returned is is the
        midnight at the end of the date reported, conceptually as if the time portion
        were "T24:00:00".
      </xhtml:p>
    </output>
  </signature>

  <error code="xfie:PeriodIsForever">
    <xhtml:p>
      This error MUST be thrown if the item is reported with a forever
      period.
    </xhtml:p>
  </error>

  <conformanceTest xlink:type="simple" xlink:href="80126 xfi.period-start testcase.xml"/>

  <revisions>
    <reg:revision on="2008-01-23T00:00:00" by="geoff">
      <xhtml:p>
        Defined the function.
      </xhtml:p>
    </reg:revision>
    <reg:revision on="2008-03-26T21:23:00" by="herm">
      <xhtml:p>
        Clarified time portion of output when only date is reported, without time.
      </xhtml:p>
    </reg:revision>
  </revisions>

</function>
